Assessing the invasive potential of Saguinus midas in the extent of occurrence of the critically endangered Saguinus bicolor

Saguinus bicolor is one of the most endangered primates in the Amazon, mainly due to threats related to human activities, such as deforestation and habitat fragmentation. Moreover, the encroachment of Saguinus midas , a widely distributed species, into the restricted range of S. bicolor , poses further conservation challenges and extinction risks. This study focuses on the potential niche overlap and competition between these two species, which are closely related callitrichid primates with a parapatric distribution. We employed the support vector machine (SVM) algorithm to investigate the potential of invasion by S. midas into the area of occurrence of S. bicolor by quantifying and comparing the habitat suitability for both species. We used environmental variables that are known to be relevant descriptors of callitrichid niches and a similarity test was applied to assess niche overlap between the two species. Our analysis reveals that the majority of the area occupied by S. bicolor exhibits higher habitat suitability for S. midas than for S. bicolor . Furthermore, we found a high niche similarity between the species. These results suggest a significant invasive potential of S. midas into the range of S. bicolor . The research highlights the concerning prospects for the long-term persistence of S. bicolor , emphasizing the urgent need for conservation measures. The conservation and maintenance of an ecologically functional urban forest matrix, along with the preservation of habitat quality and connectivity in rural areas, are crucial. Monitoring the current contact areas between the two species and the areas indicated as highly and moderately suitable for S.midas in the range of S. bicolor is also essential, and the observed trends in the occupation of these areas need to be incorporated into adaptive conservation strategies to protect less anthropogenically impacted areas. The findings are expected to contribute to the ongoing National Action Plan for the conservation of S. bicolor and support the management and conservation efforts for the species.